Some people consider themselves “a morning person”; they perform their best efforts in the early AM. Others like to hit the gym in the early evening as they feel this is the time they’re most alert and at their strongest. This is our circadian rhythm, or "internal body clock" and research shows that it has a tremendous influence on athletic performance.

Researchers have speculated that there may be a circadian rhythm inherent in athletic performance and point to research showing that athletic performance varies based on time-of-day. To better understand the potential existence of a circadian rhythm in performance, a group of researchers from the University of South Carolina, assessed 25 highly trained swimmers over 50-55 consecutive hours.

Results showed that swimming performance had significant circadian variation when expressed relative to the time of day. Specifically, swim performance was impaired between 2:00 - 8:00 AM, compared to all other times of day. Peak performance was at 11:00 PM.

Before you go scheduling midnight workouts, remember that circadian rhythms are malleable, and the body actually re-sets its circadian rhythm every 24hours. That means, over time you can train your body to perform best at what ever time of the day is best for you. The trick for competitive athletes is to train at the same time of the day that they compete. This will teach their body to perform best at the right time of the day.